Power control for aircraft engines



April 16, 1946. v s. v. MADDox I vPOWER CONTROL FOR AIRCRAFT ENGINES 2 Sheets-Sheet l Filed Aug. 29 1944 A NN l'hvr April 16, 1946. v. 'MADDox I 'l Y PowEnlmnoL Fon AIRCRAFT ENGINES Filed Aug. 29, 1944 2 Sheets-'Sheet 2 Patented Apr. 16, 1946 l-Stitnl'e`-y Victor Maddox',

England, assigner to H Clieylesmore, .Coffman M. `Holzman moratti; y'

Motor) Components Limited; ltoxldon- England Application August 29, 194'4", Serial No. 55h70?" In Great Britain January 1, 11944 s claims. tcl. lice-ical l This invention provides, in or for an aero engine, the combination with a vane-type servo motor, the operating valve whereof is coupled to `a`-pilots throttle lever so as to lbe actuatedl by movement of said lever and the vane whereof serves to control the positionvoi" the throttle valve, of a stop for arresting the vane when the pilot's lever, on movement to close the throttl'e has reached the slow running. position and. a linger operatively connected to the operatingvallve or to the pilotrs lever and arranged to actuate a fuel cut-olf valve on further movementl of the pilot's lever beyondV the slow running position.

Itis preferred to provide aspring-loadedplunger which is displaced by the vanel on movement thereof into the. slow running posi-tion, and is elective to move the vane into the start position should uid pressure be out oft` from the servo motor while the vane is in thel slow run.-

ning position, the vane being mechanically connected to the throttle. so as to openthe latter to a position suitable `for starting when moved by the plunger into the start position.A i

It is also preierred to provide the operating A r 23 toothed quadrant" r9 meshing with o, toothed valve with a projection, having. a restricted range of movement` between-stops on the surrounding sleeve carrying the vane said. projection cooperating with the stops to7 permit of manual operation of the vane by the pilot-s lever the event of failure of ther iiuid pressure.

Two formsof power conti-fol for aero' engines according to the invention will now kbe described iny detail by way of. example,` with reference te they accompanying drawings, in which: f

` Fig. 1 is a `diaglsammaticlayout of the Erst irr-r stallation, Figs. 2l and 3 aresections` on an; enf largedscale taken respectively on, the lines LI-II and III-#Ill in Fig. l, and Flare isa diagram. matic layout of the second installations A Like reference characters indicate like `parts throughout the gures; t u

In Figs. l and 4 the lparts are shown inthe posi.-

Y tion theyl occupy with thepilot's: throttle rever n the slew-running' position, while in Figa 2 and 3 they are' shown in' the alternative positions. which they assume when the pilots throttle lever is in the cut-offl position.

The power control illustrated in Figs. 1-3 is actuated by' a pilots throttle lever IU, movable about a pivot Il. 'I'l'iisv single lever controls, through the agency'of a master servo motor l2', mechanisms for `centre!ling the' following" engine functions: j P (a) 'The boost pressure, andclegreeA of openthe required boost pressure at the `altitude at which the aircraft flying:

i (d) The cnaneefoveryiirtlreg'ear ratio the blower fitted to the ennuie. y y

The pilots throttle fever 'It is movable between the slow-running and take-olf positions shown in Fig. 2, and' operates'tlrrou'gli tllejagency of the m1 master servo motor f2' nto adjust the above-iiidicuteci; engine functions; appropriately to conform with the position of said lever, in the same fashion :as tliepilots throttle level in the casel of V theiin'stall'ation described in oopendin'fir applica'- 1'5. tion `s'eria No. 551;'103, but tnrougfr the `agericxr ofoinerent mechanism. The lever fc' ls also movable Beyondl the slow-*running position vinto a cutoff position in which Vit cuts-off" the now ofrv fuel to the'engine.4 v '2o Fuel is normally` fed to tno induction ple f4` through a pipe l5 ternniiating in an injection nozzle f6'. In `tliepipe Vraisn locatedV a cnt-off valve IT which is normally` maintained open by' a spring t8 (see Fig, Ii. v'I'lie lever 'Hr carnes a quadrant 2U fixed. to the operating valve if of the masterf4 servo motor. 'Y Pivotal movement of tiie "liever lo nierefore effects rotation `of tlie valve 2T. *Ilo tjlie valve' '2f is Hired a linger z2.

ringer is maintained clear of" the stein 23 of the valve* f1. when the pilois` lever' tu occupies a; position between.4 the slow=runnine and takeon positions, so that the valve fr is open.

Y Y V however the lever fo is moved' beyond the slow 35 running l'aositon and into the cut-off' position,

the finger zfpresses ae'a'nsttlie stem 23 ofthe valve I1 and closes tnelatter (seeligym, thereby cutting off the fuel'suiiplir. l v

The master servo motory fz' o1"` tlielvogg fy lio and comprises the usuals'civo vane 2t rotatably mounted ill 'a correspondingly shaped housing 25 and fixed. to a sleeve It surrounding fthe valve 2L (see Fig; 33"', The' valve flhasffour axially extending grooves, separated by landsi Qne pair 5 of opposite grooves 2LT is closed at the upper end andv open at the lower end to ani oil pressure inlet MLV 'The other two groovesI 29y which alternate with the groovesffl.` are closed?` at their lower ends' and open at their upper ends to an exhaust 50 outlet The sleeve 2`6 is formed with. ports 3|V communicating with the housing 25 on `opposite sides oft` the vane 241 .Normally these ports are masked by ad'oinlng: lands of? the valve. 'On rotationv ofthe; valve fr" one of the ports 3l will ingof" tno throttle valve F3 necessary to establish so be open to a pressure groove and' the other to an Aexhaust groove, and the vane will turn, following the movement of the valve, until the ports 3l are once more masked by the lands.

When, however, the vane 24 reaches the slowrunning position, shown in full lines in Fig. 3, it is arrested by a stop 32. In this position the grooves in the valve are located as indicated in chain-dottedlines. On further movement of the pilots lever I into the cu -ofl position; the vane is unable to follow the valve, which moves on into the position shown in full lines in Fig. 3. Y

A plunger 33 loaded by a. spring 34 normally projects inwardly into the 'housing 25,'but is pushed aside by the vane, as shown in Fig. 3, when the latter moves into the slow-running positions; Should the fluid pressure be cutoff with the vane r in this position, the spring 34will return the vane to the start position (shown in chain.-dotted lines in Fig. 3) thus opening the throttle through the mechanism later described to a position suitableforstarting.`4 Y To an extension' 35'ofithe vane` sleeve 26 are fixed an eccentric 36 and'foiircams'31f40. Embracing the eccentric 36 is'fa'strap'11`connected to the throttle I3an`d toi thelservofpiston-M of a vala/ble datunboost 'nto1-42'by`the connections .indicated diagamratically at l43` and Y 44 respectively.` i 'A 1. 'i vr' The eccentricY 3`6"perx nits` theservo vane 24 to effect a limited mechanical opening of the throttle valve,` as the pilots lever is opened up from the slow'running position, as' described in Vapplication Serial'No.' 530,428. Thereafter the major movement off the throttle vvalve is exe'oted by the servo pistonAl of the boost control likewise `Aas Ydescribed in" 'application Serial No. 530,428. The mechanical movement through theageIiCy olfftheV eccentric 36 .is eective to open the throttle Vvalifnej to a starting position, when the spring loadedplu'nger 33 comesinto operation, on failur'jof thefluid l Y to an arm 'for'effecting the gear change. The

pressure," as described above.

i' Theboost control is of the variable datum type, similar, to that described in U; S. Patent No. 1,995,V 800,1and comprises the Lusual 'capsule' stack 45, located in a chamber46 open to boost pressure through anlinlet 41, and relay valve'48 for actuatingjthe-A servoipistfo'n 4I. The datum of the boost control is varied in 'accordance with the position of the pilots'leverjl through the agency'of a belljcrank lever 49 pivoted' at '50 and operatedfby thecam 40, through the agency of a Vfollower 'mounted Vuna bifurcatedlever 5l" 'pivotedona shaft52 and lconnected to the' bell crankby a 'connection'shown diagrammatically at53j.

j iIhe'shaft'Z, is rotated by means of a follower on LaA lever 54"'xed tothe shaft,'vwhich`follower`:co-l operates with the cain38. The shaft 52 is coupled to the controlling valve'f55V of 'a vane' type servo "in or 56 for controlling the engine speed and serves torot lve 55. The servo vane 51 of this" servo motor has at itSfSleeVe 58an arm l59 which servesto varythe en '.1' speed by adjustment o fthefsetting of'a; governor associated with the'variable' pitch airscrew. The relationship betweenenginejspeed and boost pres'- sureis determined bythe :contour of the speed cam 38 andby that of the boost datum Vcam 40.` The construction and operation of the servo motor 56 are fully described in application Serial 150,551,703 and it will be sufiicient heretostate that sleeve 56, likethe sleeve 26 ofthe master servo motor l2, has ports (not shown) communieating with the housing 'of the vane 51 on opposite sidesj of said vane. y These ports are normally masked by the vlands on yv lve, A'. ,but 1011; IO'GM'QH of said valve are connected alternatively to pressure and exhaust by the grooves in said valve, so that the vane 51 is caused by the fluid pressure dilerence so established across it to follow the rotational movement of valve 55, the vane turning until the ports are again masked by the lands on the valve. Servo motor 56 differs from servo motor I2I only in that the 'grooves in its Vvalve 55 are helical instead of being .axial asin the case of valve 2l. The arm 59 operates, on rotation of vane 51, to vary the adjustment of the governor'controlling the pitch of the airscrew blades, and so to vary the engine speed, likewise as described in application Serial No. 551,103.

, The valve 55 is coupled, by a connection shown diagrammaticallyat 60 to an override lever 6|, which is normally latched in Ithe position illus- -`trat'ed by a spring detent 62 and thus prevents 'the'valve' 55 from moving axially. The lever 6l is movable to override the automatic setting of the engine speed, by .imparting axial movement to thefvalve'55, so'as tojfeather the airscrew blades or set them at iine pitch asl may be desiredfor emergency purposes, and 4as described in copending applicationSerial No. 551,103. The amount of Voverride obtained for a given movement ofjthe lever 6l is determined by the helix angle of the valve 5,5.

The cam 39 controls the ignition timing. It cooperates with a follower on a lever 63 pivoted on the shaft 52 and connected, by a connection not shown, to the magneto. c i

The fourth cam 31`jserves to vary the datum of a stack of capsules 64 located in a chamber 65 exposed to atmospheric pressure through an inlet 66 land controlling a blower gear change mechanism through the agency of a piston valve 61, vane typeservomotor and rotary shuttle valve 69 as described in copending vapplication 'Serial No. 551,706; Thevane 68of the servo motor is fixed datum of the capsule stack*r 64Y is changed by a bell crank lever 10 pivoted at 1l and connected, by a connection 'shown diagrarrunatically at 12, to a lever 13 pivoted onthe shaft 52 and carrying a follower cooperating with the cam 31. An override lever is provided Vfor manually overriding the automatic gear change as described in application Serial No. 551,706. I Y

The valve 2l carries (FigfZ) a flnger 14 projecting through a slot15 in the sleeve 26 carrying the-vane 24 of the master servo motor. Stops 16dening theends ofthe sl`ot15 in the sleeve cooperate with the finger v14 to limit the extent to which the valve 2 I can vrotate in relation to Y the vane 24. These stops permit of manual operation of' the fvane 24 from the pilots lever Ill in` case `of failureofthe yfluid pressure in the master servo. VProvided pressure fluid is ,still available in -the other servos, the pilot thusstlll has a considerable measure o f controlA vover the engine, and even if pressu'Qhas failed throughout e v aulic 'systemjthe pilot vstill retains somernanualcontrov v'i'ition of the^throttle. The stops 16 also permit the pio.. to return the vane 241to thejstart position should theengine cut out when the throttle'is` in some more open position.

j. The alternative installation shownY in Fig. 4 is y similar in itsessentialsto that of Figs. 1-3. In

this,` case, howevenithe, operating valve 55 of the ser-vio motor 56 for, controlling .the engine speed receives an axial movement to operate the servo motor from an arm18 fixed to the shaft 52. i The u entgangenen@gesteundhommessure is ydeterminedby thelhelix angleof the valve 55 in conjunction with fthe contour of the speed cam -38 and 'that ofthe boostdatum cam 4U. The valve "55 is ycoupled to theoverrde lever -6I, as -described in application Serial No. 551,704'by-'a Aconnection allowing-of axial but not rotational `movement of the valve 55 in relation to the lever 8|, which is 'normally .latched in `the Auto position. The Aoverride mechanism operates by imparting rotation to the valve `55 as described in saidapplication Serial No. 551,704.

:The fuel cut-off valve l'Iis closed, against the action of its spring I8 to cut ol the flow of fuel tothe induction pipe through the pipe I5, when the fp'ilots lever moved tothe cut-oil position by a finger 19 fixed to a lever `80, which Ais rocked about its pivot AL8-I by a link -82 operated by .a pivoted arm 83. This icarries a dog 9| which is engaged by a .dog 92 fixed to the pilots lever Ill, when the latter 'is moved from the slow running to the cut-olf position, so fas to rotate the arm 83 y and draw the 82 to `the leftas seen in Fig.

4. The link 82 also operates, when drawn to the left, a lever 84 to close a valve 85, and so interrupt the supply of fluid to the master servo motor I2 through the pipe 38 when the pilots lever Il) is moved to the cut-oi.F position.

It is desirable to cut off the master servo in this way when the pilots lever is moved to the cutoff position. Otherwise when starting the engine on the fuel priming system oil pressure would be immediately transferred to the servo motor and would maintain the vane in the position shown in Fig. 3 in which it overcomes the springloaded plunger 33 and closes the throttle so stopping the engine. When this servo cut-out is employed the operation is as follows:

When starting up the engine, the pilots lever is back in the start position (intermediate between the cut-olf and slow running positions) and the fuel and servo fluid are both cut oil. The engine is turned over and started on the priming system and, as soon as it is firing, the pilots lever is moved forward to the slow running position, when both fuel and servo uid are turned on and the servo motor positions the throttle in the slow running position.

A stop screw 86 is provided for preventing the throttle valve I3 from closing beyond the slow running position when the pilots lever is moved to the cut-off position, the servo piston 4I remaining at the right hand end of its cylinder, to which position it is biased by a spring 81, as illustrated, when the pilots lever is moved beyond the slow running position and into the cut-olf position.

The inlet 66 for supplying air at atmospheric pressure to the casmg 65 communicates, as shown, with the air intake 88 of the induction pipe.

What I claim as my invention and desire to secure by Letters Patent is: l

1. A power control installation for an aero engine comprising the combination with a throttle valve and a pilots throttle lever movable between an open throttle position and a slow running position and beyond the slow running position into a cut-off position, of a vane type servo motor having an operating valve coupled to said pilots throttle lever so as to be actuated by movement thereof and a servo vane operatively connected to said throttle valve, a stop for arresting the vane when the pilots throttle lever, on movement to close the throttle valve, has reached the slow running position, a normally open fuel cut-off valve, and a finger operating, on movement of thefpilots throttle lever from. the slow running'to Af'tlie 'cut-oil' position, f to close said cut-offivalve. Av1 l H "2. 1A `power control installation for antaeroengine comprising the -cc'imbinationfwith .a `throttle valve and a pilots throttle lever movable between an open throttle position and a slow .running position and beyond .the slow running position into a cut-off-position;oalvane typeservo motor having an `operating `valve coupledto said pilotsthrottle lever so' as Lto be actuated by movement thereof and la-'servol vane operatively connected torsad throttle valve,-a stop for arresting the vane 'when the pilots throttle lever, on movement -to Aclose the throttle' valve, has reached the slow running position, `aspring'- loaded plunger arranged tobe displaced by the vane on movement thereof into the slow running position, but operative lto move the vane into a predetermined position Aon failure Aof the iluid pressure in the servo motor while the vane is in the vslow running position, a mechanical connection between the vane and-"thethrottle valve for moving rsaid valve to a'position suitable for starting the engine on movement of the vane into said predetermined position by said plunger, a normally open fuel cut-off valve, and a linger operating, on movement of the pilots throttle lever from the slow running to the cut-off position, to close said cut-01T valve.

3. A power control installation for an aero engine comprising the combination with a throttle Valve and a pilots throttle lever, of a vane type servo motor having an operating valve coupled to said pilots throttle lever so as to be actuated` by movement thereof, a sleeve surrounding said operating valve, a servo vane attached to said sleeve and operatively connected to said throttle i valve, and a projection on said operating valve having a restricted range of movement between stops on said sleeve, said projection cooperating with said stops to permit of manual operation of the vane by said pilots lever in the event of failure of the fluid pressure in said servo motor. Ll. A power control installation for an aero engine comprising the combination with a throttle valve and a pilots throttle lever movable between an open throttle position and a slow running position and beyond the slow running position into a cut-off position, of a vane type servo motor having an operating valve coupled to said pilots throttle lever so as to be actuated by movement thereof and a servo vane operatively connected to said throttle valve, a stop for arresting the vane when the pilots throttle lever, on movement to close the throttle valve, has reached the slow running position, a normally open fuel cut-off valve, a normally open valve for supplying pressure fluid to said servo motor, and means for closing said cut-cit valve and said normally open valve onmovement of said pilots throttle lever from the slow running to the cut-off position.

5. A power control installation for an aero engine comprising the combination with a throttle valve and a pilots throttle lever movable between an open throttle position and a slow running position and beyond the slow running position into a cut-off position, of a vane type servo motor having an operating valve coupled to said pilots throttle lever so as to be actuated by movement thereof and a servo vane operatively connected to said throttle valve, a stop for arresting the vane when the pilots throttle lever, on movement to close the throttle valve, has reached the slow running position, a boost control device, means `for varying the datum of said boost controldevice on movement of said servo vane, a normally open fuel cut-off valve, and a linger operating, on movement of the pilots throttle lever from. the slow running to the cut-off position, to close said cut-off valve. Y Y

6. A power control installation for an aero engine comprising the combination with a throttle valve and a pilots throttle lever movable between an open throttle position and a slow running position and beyond the slow running position into a cut-off position, of a master vane type servo motor having an operating valve coupled to said pilots throttle lever so asto be actuated by movement thereof and a servo vane operatively connected to said throttle valve, a, plurality of slave servo motors each for adjusting a separate engine control and all connected to the servo vane of the master servo motor so as to be operated simultaneously under the single control of said pilots throttle lever, a stop for arresting the vane when the pilots throttle lever, on movement to close the throttle valve, has

reachedvthe yslow running position, a normally, open fuel cut-01T valve, and a iinger operating, on movement of the pilots throttle lever from the slow running to the cut-off position, to close. said cut-,oir valve. f d Y '7. Apparatus asY claimed in claim 6, which includes ra pair of slave servo motors arranged respectively to vary the boost pressure and engine speed as desired functions o f the position of the pilots throttle lever. i 8. Apparatusas claimedin claim 6, in which one of the slave servo motors is associated with a b oost control device and operates to position the throttle valve and comprising a blower, means for changing the gear ratio thereof, a servo motor for operating said gear changing means, a stack of capsules responsive to atmospheric pressure for. actuating said servo motor, to eiect the gear change at a predetermined altitude, and means controlled by the servo vane of the master servo motor for changing the datumof said stack of capsules as the boost pressure Varies. l

STANLEY VICTOR MADDOX. 

